Removing the direct SQL query in `do_all_pings()` improves filterability.
As part of this change, the signature of `do_enclose()` is changed so that
a null `$content` parameter can be passed, with the `$content` then inferred
from the `$post` passed in the second parameter. In addition, the second
parameter was modified so that a post ID or a `WP_Post` object can be
provided. These changes make it possible to trigger enclosure checks with
a post ID alone (as in `do_all_pings()`) and also brings the function
signature in line with `do_trackbacks()` and `pingback()`.
Props dshanske, spacedmonkey, janw.oostendorp, mrmadhat, birgire.
See #36824.
git-svn-id: https://develop.svn.wordpress.org/trunk@46175 602fd350-edb4-49c9-b593-d223f7449a82